Various means have been used in the past to acquire accurate data regarding a shell's in-bore environmental experiences in order to decrease the frequency of in-bore malfunctions and prevent either unnecessary rejections of munitions or the production of overdesigned munitions. One of the problems with prior art devices which used hard wiring from the projectile transducers up the gun tube to recording equipment was that it was practical only for lower zone firing tests. When the aforementioned prior art devices were used for high zone firings, the higher stress forces invariably resulted in wire breaks and consequently loss of test data. In addition, because of wire breakage the test data of the induced strain, caused by the stress environment that a shell experiences when exiting from the gun tube, could not be measured. Other prior art devices utilize R.F. transmission of in-bore shell strain measuring transducers to transmit test data to out of gun tube recording equipment. The problem generally found with this technique was the effect of the gun tube acting as a wave guide. The wave guide effect would frequently short out the R.F. test data signal at various points in the gun tube as the transmitting elements of the projectile traveled up the tube. In addition, blow-by-gases seeping around the shell usually caused further alteration of the R.F. test signal. This shorting and alteration effect on the transmitted R.F. signal was particularly noticeable in worn gun tubes. As a result of the aforementioned problems only limited test data coverage was possible and frequently the information transmitted on this limited signal was made additionally uncertain because of a noisy signal. Other prior art devices have used laser devices to transmit in-bore test data out of the gun tube to recording equipment. The major difficulty with the use of this technique was the critical alignment requirements of the transmitter and its receiving station. In addition blow-by gases leaking around the projectile as it traveled up the gun tube usually obscured and attenuated the laser light beam and resulted in further data loss.
In the past digital delaying techniques have been used on missile programs to delay transmission of data until R.F. transmission conditions were optimized. However, the prior art delay techniques required that the data be first sampled and digitized by use of an analog to digital converter and then by using digital shift registers delay the data transmission an appropriate amount. The data then had to be reconstructed by use of a digital to analog converter. This prior art technique of delaying data has been found to be costly, complex, and too large to be effectively utilized in in-bore projectile telemetry requirements.